Method of manufacturing briquettes and other bodies from serpentine



1 METHOD OF MANUFACTURING BRIQUETTES AND OTHER BODIES FROM SERPENTINE Merton 'H. Davey, Mechanicsburg, Pa, .assignor'to- D ;& P

Minerals, Inc., Harrisburg, 'Pa., acorporation .of Pennsylvania Serial No. 761,286

8 Claims. (Cl. 75-3) No Drawing. Application September .16 1958 This invention relates to the manufactureof briquettes and other bodies from serpentine which ,is, of course,

wholly or principally of vForsterite which is a magnesium silicate, Mg SiQ the said body having remarkable refractory properties and being characterized ,not only by mechanical adhesion and improved crushingstrength, but by a ,bond wherein there is an actual chemical integration of the particles at their interfaces.

results in a manner which is both simple and inexpensive. As an example of .the great utility of the method'of the present invention, chrome .ores may be very .eifectively briquetted thereby.

As is well known, chrome ores are quite expensive;

and very substantial quantities thereof assume a powdered or finely divided form which renders them either undesirable or completely unfit for various .uses. Such ores are, in many instances, homogeneous mixtures of Cr O FeO, CaO, MgO, SiO A1 0 and any additions of Fe (iron), Ca (calcium), Mg (magnesium) or ,Si .(silicon) depreciate their salable value.

The most common chrome ore gangue rnat erial is, of

course, serpentine which, as before mentioned, consists essentially of a hydrous magnesium silicate, H Mg Si O According to the teachings of the present invention, certain chrome ores-containing serpentine (such, for examp as :antigQrit from the .areanftEaston, Penn y vania) may be so bri quetted asto-acqnire a bond of the type referred to hereinbefore in which recrystallization produces a Forsterite structure. As will be understood by those skilled in the art, such briquettes are highly desirable for many commercial operations.

I have obtained excellent results by adding to finely divided chrome ores containing serpentine borax approximating 25% of the contained serpentine, and hot water in the ratio of approximately 6% by weight, then thoroughly mixing the mineral composition and forming it into briquettes of the desired size and shape, the briquettes so formed then being dried and fired at temperatures as low as 650 C. However, acceptable results may be obtained with the inclusion of borax ranging between approximately 0.5% and approximately 1.5%.

It will be understood by those skilled in the art that temperatures even lower might be utilized, provided the briquettes are subjected thereto for a sufiicient period of time.

If desired, bentonite in the amount of 0.5 to 1.0% may be supplied before the hot water is added simply to enhance plasticity and improve the green strength of the briquettes, this being disclosed in my patent application Serial No. 689,781, filed October 14, 1957, now abandoned, and in my patent application Serial No. 707,670, filed January 8, 1958.

The serpentine treated in the foregoing example was I Ratented Mar. 24, .1959

the natural state, having had no prior chemical treatm i l- I I .It will be understood that there may be utilized chrome ores. of different, but appropriatehquality which are mixed in the natural state, the ratio of around 3 chromium .to 1 iron being observed in the manner well known in the art.

As illustrative of the advantages set forth earlier here.- in, two briquette samples produced in accordance with the teachings of. the present invention were heated to temperatures of approximately 850 C. and approximately 1200 C., respectively, the first sample being found to have acrushingstrength .of approximately 3000 pounds per square inch, and the second sample a crushing strength of approximately .8000 pounds per square inch.

"Therefore, the strength .of the bond produced by the I 1 a glass with the borax, the glass having an increasing Another object is the attainment of the foregoing and they become closer .knit instead of disintegrating, as

'1 has been the problem of the binders of the .prior art.

, Differential thermal analysis studies of pure chromite show no deflections in the .curves, demonstrating that the reactions determined for chromite ore are actually those of the gangue, i.e., the impurities, non-chromite minerals, and oxides, .etc., of the ore. Thenormal almost universally found .ganguein chromite ore is .serpentine. Ditferential thermal analysis studies off-typical chrome ores yield similar curves. I,

Comparison of the aforementioned curves of typical chromite :ore with curves published in the book The Differential Thermal Investigationof Clays, editedgby Robert (3., MacKenzie, ,published by the Min. Soc. London, 1957, indicatcsithe ore curves to bethose of se pentin hi i sm n sfi e the nns-90minq s om a e angu m ra The exothermic peak at 815 C. is caused by crystallization of the amorphous material to Forsterite, Mg SiO I have discovered that borax, when used in the manner described hereinbefore, so reacts with the serpentine gangue as to flux the crystallization of Forsterite at temperatures of about below normal. On the diflFerential thermal analysis traces, the addition of borax to serpentine (l) Subdues the endothermic peak at 690 C.; and

(2) Subdues and lowers the temperature of the exothermic peak (700-815 C.).

Boron is classically a mineralizer in that it fluxes crystallization reactions; and it, therefore, appears that serpentine, upon dehydroxylization, immediately crystallizes to Forsterite due to the presence of borax as used in the manner described. This explanation requires that the endothermal dehydroxylization and exothermal crystallization occur penesirnultaneously. If so, the complete reaction would take place-in the 650-705 range. X-ray studies have proved .this to be true.

Accordingto the teachings of the present invention, ordinary (or pure)'-sei'pentine may, throughthe use of borax, etc., in the manner described, be converted to Forsterite andquartz, SiO 'or burned magnesite, MgO, added to obtain a refractory body (such as fire brick) which is (at least theoretically) entirely'Forsterite.

While I have shown and described certain specific embodiments of the present invention, it will be readily understood that I do not wish to be limited exactly thereto, sincevarious modifications may be made without departing from the scope of theinvention as defined in the appended claims.

i I claim: V,

A method of briquettingserpentine which includes mixing therewith approximately 0.5% to approximately 1.5% of borax, adding water to the aforesaid mixture, t

the water-containing composition, and forming'it into briquetttes, drying said briquettes, and firing said briquettes at temperatures ranging upwardly from about 650 C., thereby fluxing the crystallization of Forsterite and producing a chemical integration of the particles at their interfaces.

: 2'. A method of briquetting serpentine which includes mixing therewith approximately 0.5% to approximately 1.5% of borax, adding water to the aforesaid mixture in the ratio of approximately 6% by weight, mixing the water-containing composition, and forming it into briquettes, drying 'said briquettes, and firing said briquettes at temperaturesranging upwardly from about at temperatures ranging upwardly from about 690 C., thereby fluxing the crystallization of Forsterite and producing a chemical integration of the particles at their interfaces.

5. A method of briquetting serpentine which includes mixing therewith borax approximating 25% of the contained serpentine, adding water to the aforesaid mixture, mixing the water-containing composition, and forming it into briquettes, drying said briquettes and firing said briquettes at temperatures ranging upwardly from about 650! C., :thereby fluxing the crystallization of Forsterite and producing a chemical integration of the particles at their interfaces.

6. A method of briquetting serpentine which includes mixing therewith borax approximating 25% of the contained serpentine, adding water to the aforesaid mixture in the ratio of approximately 6% by weight, mixing the water-containing composition, and forming it into briquettes, drying said briquettes and firing said briquettes at temperatures ranging upwardly, from about 650C., thereby fluxing the crystallization of Forsterite and producing a chemical integration of the particles at their interfaces.

7. A method of briquetting serpentine which includes mixing therewithborax approximating 25% of the contained serpentine, adding water to the aforesaid mixture, mixingthefwater-containing composition, and forming it into briquettes, drying said briquettes, and firing said briquettesat temperatures ranging upwardly from about 650 C., thereby fiuxing the crystallization of Forsterite and producing a chemical integration of the particles at their interfaces.

3. A method of'briquetting serpentine which includes mixing therewith approximately 0.5% to approximately mixing the water-containing composition, and forming it into briquettes, drying said briquettes, and firing said briquettes at. temperatures ranging upwardly from about 690' C., thereby fluxing the crystallization of Forsterite and producing a chemical integration of the particles at t I water-containingcomposition, and forming it into br'i- "o quettes, drying said briquettes, and firing said briquettes 690 C., thereby fluxing the crystallization of Forsterite and producing a chemical integration of the particles at theirl interfaces.

8.)! method of briquetting serpentine which includes mixing" therewith borax approximating 25% of'the con- 1.5% of borax, addinglwater to the aforesaid mixture,

tained serpentine, adding water to the aforesaid mixture in the ratio of approximately 6% by weight, mixing the water-containing composition, and forming it into briquettes, drying said briquettes, and firing said briquettes at temperatures ranging upwardly from about 690 C., thereby fluxing the'crystallization of Forsterite and producing a chemical integration of the particles at their interfaces.

References Cited in the file of this patent FOREIGN PATENTS 9,210 Great Britain Apr. 18, 1906 17,246 Great Britain Aug. 11, 1908 19,351 Great Britain Sept. 3, 1902 

1. A METHOD OF BRIQUETTING SERPENTINE WHICH INCLUDES MIXING THEREIWTH APPROXIMATELY 0.5% TO APPROXIMATELY 1.5% OF BORAX, ADDING WATER TO THE AFORESAID MIXTURE. MIXING THE WATER-CONTAINING COMPOSITION, AND FORMING IT INTO BRIQUETTES, DRYING SAID BRIQUETTES, AND FIRING SAID BRIQUETTES AT TEMPERATURES RANGING UPWARDLY FROM ABOUT 650* C., THEREBY FLUXING THE CRYSTALLIZTION OF FORSTERITE AND PRODUCING A CHEMICAL INTEGRATION OF THE PARTICLES AT THEIR INTERFACES. 